1. Field of the Invention
The present invention relates to a target value control system for a transmission power control and a method thereof and a base station and a mobile communication terminal, and in particular, it relates to a target value control system for a transmission power control in a W-CDMA communication system.
2. Description of the Related Art
In general, in a portable type mobile station and a radio base station (hereinafter simply referred to as base station) of a W-CDMA (Wideband-Code Division Multiple Access) communication system, a transmission power control function for controlling transmission powers of respective distant stations is built. This is a function to control the transmission power of the distant station so that a reception quality satisfies a target reception quality in a local station. Here, the target reception quality is set for a mobile station and a base station from a network. For these transmission power controls, there have been several proposals submitted.
For example, in Patent Document 1, there has been proposed the operation of a basic transmission power control. To be more specific, when the current reception quality does not satisfy the target reception quality, a target SIR (Signal to Interference Ratio) is increased, and when the target reception quality is satisfied, the target SIR is decreased. By comparing the adjusted target SIR to a reception SIR, a TPC (Transmission Power Control) bit for controlling the transmission power of the distant station is decided, thereby controlling the transmission power of the distant station.
In this Patent Document 1, as a technique for enhancing measurement accuracy of the reception quality, there is an attempt made to satisfy the target reception quality by finding a moving average of the number of reception errors (corresponding to the reception quality) in a certain constant section.
[Patent Document 1 ] Republication of PCT Application No. WO 97-50197